Lennox S40 - Page 74

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Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting
E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system,
SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender
Alert
Code
Inverter
Flash
Code
Priority
Condition
Actual Displayed Alert
Text Under dealer control
center > Notications
Component or System Operational State and Troubleshooting Tip
How to clear
alert code
432 28
Service
Soon/Service
Urgent
OU Inverter DC Link
High Voltage
The inverter has detected a DC link high voltage condition.
• Error occurs when the DC link capacitor voltage is greater than 480 VDC.
• If condition is detected, outdoor unit will stop (compressor and fan) – service soon condition.
• Anti-short cycle timer is initiated.
• If condition occurs 10 times within 60 consecutive minutes, the system will lockout – service urgent
condition.
• Inverter LEDs will ash code 28.
• Refer to the unit service documentation for detailed troubleshooting procedures.
Inverter ash code 28.,
The sequence is:
• Red LED: Two Flashes
• Green LED: Eight Flashes
NOTE: Inverter normal operations with no error code present is as follows. Red LED is ON and Green LED
is OFF.
Troubleshooting Suggestions:
• Check wire connections (U, V and W) at inverter plug in harness and compressor.
• Check the resistance of compressor windings. If not in range, replace compressor.
• Check compressor to ground. If ground issue, replace compressor.
• Check input power (Single Phase - 208/230VAC + 10%. If out of range, correct main power issue.
• Check DC Link voltage and MICOM Sensing voltage. If out of range, replace inverter. if okay, possible
mechanical issue with compressor.
Go to outdoor unit service manual for detail troubleshooting procedures and require values for testing DC link
voltages and various insulation resistance characteristics.
To clear, disconnect
power to outdoor unit
and restart.